1.1.b Flashcards
Atria
Blood enters, atria contract and squeeze it into ventricles
Muscular Walls of the heart
Thin around the atria, thick around ventricles (especially left!!) , pushes blood into ventricle
Ventricles
Need to push blood to a further distance, require more force
Right ventricle
Pushes blood into pulmonary artery
Left ventricle
Pushes blood into aorta
Aorta
Biggest artery in body, sends blood around every part of body
Atrioventricular valves
the valves between atria and ventricles (tricuspid and bicuspid valves)
Semilunar valves
the valves between the
ventricles and the bloods ‘exit point’ of the heart
Veins
Carry blood towards the heart
Arteries
Carry blood away from heart
Vena cava
Biggest veins in body
Superior ->returns blood above heart
Inferior -> returns blood below heart
Pulmonary artery
Sends used blood (full of waste products and lactic acid) to lungs that cleans & replace it with fresh oxygen
Lungs
Send the new washed blood back to the heart through pulmonary veins
Pulmonary veins
bring the new blood back to the heart, which enters through the left atrium, which pushes the blood down into the left ventricle, which sends it up to the Aorta.
Aorta
sends the new blood, rich in oxygen, away from the heart, around the body to all our muscles and organs
Heart values
Heart rate, stroke volume, cardiac output
Heart rate
Bpm.
Resting; between 60-100
Stroke volume
Amount of blood pumped out of heart (left ventricle)
Avg: 70ml
Cardiac output (Heart rate * stroke value )
Volume blood pumped out of heart per min (l/min)
Cardiac cycle
The transport of blood to the lungs and other working muscles of the body
Diastole
Lub (heart relaxes and fills with blood)
Systole
Dub (heart contracts and ejects blood)
Atrial systole
atria contract which forces blood into the ventricles
Ventricular systole
ventricles contract which pushes blood out of the heart to the pulmonary artery and aorta.
Conduction system
Myogenic/intrinsic
signal is sent across the heart by the cardiac muscles
Sino-atrial node
often called the ‘pacemaker’. Regulates the heart rate in line with the body’s demand. Sends out an electrical stimulus which travels across the muscle cells in the atria, causing the atria to contract (atrial depolarisation)
Atrioventricular-node
The impulse travels to the AV node, where it delays the next contraction to allow the ventricles to fully fill with blood. Once the AV valves have closed, the stimulus travels to the bundle of His and Purkinje fibres.
The bundle of His
are found in the ventricular walls and cause ventricular contraction as a result of conducting the electrical impulse in the ventricles (ventricular depolarisation)
Purkinje fibres
The stimulus travels down the bundle of His, which is a group of conduction cells. This separates into the right and left branches which consist of the Purkinje fibres
Atrial depolarisation
The effect that the SA node has on the atria, causing them to contract by providing an electrical stimulus across them
Ventricular depolarisation
the effect that the AV node has on the ventricles, causing them to contract by providing an electrical stimulus
Atrial and ventricular repolarisation
occurs during a brief time period following depolarisation, and describes the electrical impulse returning to a baseline value
Anticipatory rise
Heart rate before exercise going up
Plateau
Heart rate matches oxygen demand during exercise
Recovery
After exercise heart rate remains elevated for periods of time, waste products removed and oxygen debt paid
Vascular shunt mechanism
Shunts oxygenated blood to muscles that need it most.
vasomotor centre
In medulla olongata, regulates the blood flow by causing the sympathetic nervous system to cause arteries to either vasoconstrict or vasodilator
Precapillary sphincters
smooth muscle surrounding the intersection between the arterioles and capillaries.
When arterioles widen or narrow to help control blood flow towards capillaries
Venous return
the rate at which the blood returns to the heart
Stroke volume ^ if venous return ^
1-5
1- valves
Restrict back flow
2- gravity
Venous return of blood in the superior regions of the body (above the heart) is aided by gravity.
3- skeletal muscle pump
Veins between muscles squeeze during contraction, causing blood towards heart againsg gravity
4- respiratory pump
During inspiration, pressure in the thoracic cavity decreases and pressure in the abdominal cavity increases. This forces blood that is inferior (below) to the heart upwards.
5- smooth muscle
Veins feature smooth muscles which help contract and squeeze the blood back towards the heart.
Frank starling law
refers to the increased stroke volume as a result of an increased amount of blood filling the heart
Venous return during recovery
Slowly decreases after exercise such as stroke volume (-> leading to a lower preloading of the heart and a decrease in the amount the ventricles can stretch before contraction.)
Neural factors
aid the regulation of blood flow, receptors send an impulse to the cardiac control centre in the medulla oblongata. This sends via symptomatic and inpathetic
Baroreceptors
sensors which detect changes in blood pressure
Chemoreceptors
sensors which detect chemical changes within the blood (i.e. high levels of lactic acid)
Proprioreceptors
sensors which detect changes in body
Position (i.e. changes in muscular activity)
Hormonal: adrenaline
released into the bloodstream and stimulates the heart. This release via the sympathetic nervous system prior to exercise is what is responsible for the anticipatory rise in heart rate
Nordrenaline
released into the bloodstream usually during stressful situations and is commonly known as the ‘fight or flight’ chemical. This increases heart rate and blood pressure.
Intrinsic factors
Increased core body temperature leads to an increase in heart rate through the stimulation of thermoreceptors, as the heart must work faster to deliver blood to the skin, to allow heat to be lost through radiation (the movement of heat from a heated surface to an unheated environment)
Nasal cavity
Right at the top of the respiratory system
Hollow space which acts as a passageway for air
The surface of this has a mucus membrane which moistens, warms and filters the air.
Pharynx/throat
Again, it has the role of acting as a passageway for air
Again, the surface of this has a mucus membrane which moistens, warms and filters the air.
Larynx
Voice box below the pharynxc, same function
Trachea
trunk’ of the respiratory tree, the trachea (windpipe) is a long hollow tubular structure which acts as a passageway for air.
The surface of this has a mucus membrane which moistens, warms and filters the air
Bronchus
Branches of respiratory tree, passageway for warm air
Bronchioles
Twigs’, distribute air throughout lungs, small thin tubular
Alveoli
Tiny air sacs which are the sight of gaseous exchange at your lungs.
Taking oxygen from the air and transferring it to your blood.
Around 480mil
Breathing frequency
Breaths per minute (not bpm!)
Avg 12 at rest
Tidal volume
volume of air displaced from the lungs during inspiration and expiration
Avg 500ml at rest
Minute ventilation (breathing frequency * tidal volume)
volume of air inhaled or exhaled per minute
Avg: 6l/min at rest
Mechanics of breathing
Gaseous exchange at alveoli
(=diffusion) alveoli takes the oxygen and diffuses it into the blood, it is also taking carbon dioxide from the blood to be exhaled out of the body.
Oxygen: alveoli -> blood
Co2: capillaries -> alveoli
Gaseous exchange at muscles
Oxygen jn blood carried by haemoglobin but dissociates (by diffusion) when delivered to muscles
diaphragm and external intercostal muscles
Responsible for breathing at rest
Sternocleidomastoid
A muscle found in the neck which helps to lift the sternum which helps to lift the rib cage, increasing the volume of the thoracic cavity.
Air moved from high pp to low (atmosphere lungs)
Pectoralis minor
Also helps to lift the sternum and therefore rib cage, once again increasing the volume of the thoracic cavity
Internal intercostal muscles
Are not activated during breathing at rest, only during exercise, helping to lower the ribs and bring them inwards, decreasing the volume of the thoracic cavity.
Recuts abdominis
Contract and cause the pressure of the abdominal cavity to increase, resulting in the diaphragm being raised, decreasing the volume of the thoracic cavity.
Chemoreceptors
detects changes in blood pH levels, as a result
of an increased amount of CO2 concentration within the blood.
This increase reduces the PP of O2, so the chemoreceptors
stimulate increase of breathing rate via the IC
Neural control: thermoreceptors
detects increase of temperature, causing respiratory rate to increase
Proprioceptors
detects stimulation of joints and muscles, stimulating the inspiratory control centre
Baroreceptors
detects the stretch of lung tissue and stimulates the ECC to cause expiration
Effects of exercise on gaseous exchange
(Pressure gradient)
Gaseous exchange occurs as a result of the pressure gradient - the difference in PP of O2 between two sites (e.g. alveoli and blood) - O2 diffuses from a site of high concentration to low concentration - the same goes for CO2
This pressure gradient is increased as we exercise, due to O2 levels in the blood decreasing and CO2 levels increasing.
(Dissociation of oxy haemoglobin)
In areas of high PP, the O2 is readily bound to the haemoglobin.
In areas of low PP, the O2 is released from the haemoglobin as the surrounding environment has a higher demand for its presence.
Bohr effect
Term used to describe the movement of the graph to the right. This ‘Bohr effect’ is a result of an increase in blood acidity, suggesting that O2 less readily binds to haemoglobin when in an environment which has low pH levels.
Affinity
Degree substances bind together
